Enantioselective synthesis of hydroxylated pyrrolidines via Sharpless epoxidation and olefin metathesis

The enantioselective synthesis of polyhydroxylated pyrrolidines from enantiomerically pure 2,3-epoxy-pent-4-en-1-ol 5 is described herein. The epoxy alcohol, readily available in any configuration by Sharpless epoxidation, was submitted to regioselective C-3 ring-opening with allyl amine, Boc-protection and ring-closing metathesis to yield dehydropyrrole derivative 7. From this key intermediate, 1,4-dideoxy-1,4-imino-d-ribitol (+)-3 and 1,4-dideoxy-1,4-imino-d-allitol (+)-4 were prepared in high yields. The enantiomers of these compounds can be obtained by the same sequence starting from an epoxy alcohol with the opposite configuration.